Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically manufactured by providing a workpiece, forming various material layers over the workpiece, and patterning the material layers using lithography to form integrated circuits. The semiconductor industry continues to improve the integration density of various electronic components of integrated circuits, i.e., transistors, diodes, resistors, capacitors, etc., by continual reductions in minimum feature size, which allow more components to be integrated into a given area.
Conductive materials such as metals or semiconductors are used in semiconductor devices for making electrical connections for the integrated circuits. For many years, aluminum was used as a metal for conductive materials for electrical connections, and silicon dioxide was used as an insulator. However, as devices are decreased in size, the materials for conductors and insulators have changed in order to improve device performance. Copper is now often used as a conductive material for interconnects in some applications. Low dielectric constant (k) materials and extra-low k (ELK) materials have begun to be implemented in some designs for insulating materials of interconnects.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.